Sear device for an automatic firearm



Sept. 10, 1957 E. c. LEE 2,805,605

SEAR DEVICE FOR AN AUTOMATIC FIREARM Filed Dec. 25, 1953 5 Sheets-Sheetl a EM INVENTOR.

H 775R NEYS Se t. 10, 1957 E. (.2. LEE 2,805,605

SEAR DEVICE FOR AN AUTOMATIC FIREARM Filed Dec. 23, 1953 5 Sheets-Sheet2 v INVEN TOR.

I v W. B Egmd -I Sept. 10, 1957 E. c. LEE 2,805,605

SEAR DEVICE FOR AN AUTOMATIC FIREARM Filed Dec. 23, 1953 3 Sheets-Sheet3 INVENTOR.

United fits-ates Patent 2,805,605 Patented Sept. 10, 1957 2,805,605 SEARDEVICE FOR AN AUTOMATIC FIREARM Edward C. Lee, Detroit, Mich, assignorto the United States of America as represented by the Secretary of theArmy Application December 23, 1953, Serial No. 400,150 6 Claims. Cl.89-136) This invention relates to automatic firearms wherein a firingmember is resiliently mounted for slidable movement in a reciprocatingbolt and is particularly directed to means for securing the firingmember in a cocked position and for the release thereof when the bolt isin a battery position.

In automatic firearms of the type described in Patent No. 1,628,226 toJohn M. Browning, there is provided a longitudinally reciprocating bolthaving a spring-biased firing member mounted for slidable movementbetween a forward firing position and a rearward cocked position. Thefiring member is arranged to be releasably retained in the cockedposition by a spring-biased sear reciprocably mounted in "erticalslideways. When the bolt is moved to the battery position, the sear isactuated by suitable means to release the firing member which movesforwardly under the bias of its spring to discharge the chamberedcartridge. During the ensuing recoil movement of the bolt, a cockinglever pivotally mounted therein, moves the firing member rearwardlyready for engagement with the sear. During counter-recoil of the bolt,the cocking lever is counter-rotated permitting the firing member to bebiased slightly forward into releasable engagement with the sear and thebottom end of such cocking lever is swung free of the firing memberwhereupon the latter is free to move forwardly when released by the searto effect another cycle of operation. b In firing mechanisms of thistype, considerable trouble has been experienced with the searprematurely releasing the firing member whereby the chambered cartridgeis not fired because the firing member does not strike the primer withsufficient force to ignite it. Further, by the sear being biased to thething member engaging position by a spring, which must necessarily exertconsiderable force thereagainst to maintain positive engagement with thefiring member, an undesirably large solenoid has to; be provided toactuate the sear when the firearm is to be operated by electrical means.Moreover, by the conventional sear being mounted in slideways, littlebearing surface is provided and therefore considerable frictional strainopposes movement of the sear.

Accordingly, it is an object of this invention to provide in anautomatic firearm bolt a scar which holds the firing member in positiveengagement until actuated by a trigger mechanism.

A further object of this invention is to provide in an automatic firearmbolt a pivotally mounted sear which reciprocates smoothly between afiring member holding position and a disengaging position.

It is a specific object of this invention to provide in an automaticfirearm bolt a pivotally mounted sear which operates without springs andwhich positively holds the sear in engagement with the firing memberuntil actuated by a trigger mechanism.

The specific nature of the invention as well as other objects andadvantages will clearly appear from a description of a preferredembodiment as shown in the accompanying drawings in which:

Fig. 1 is a longitudinal cross-sectional view of a firearm receivershowing the bolt in non-fire battery position and the firing member heldin cocked position by the sear;

Fig. 2 is a view taken along line 2-2 of Fig. 1;

Fig. 3 is an enlarged exploded view showing the mating ends of thetrigger bar and the operating solenoid;

Fig. 4 is an enlarged fragmentary view similar to Fig. l but showing thebolt in a partial recoil position;

Fig. 5 is a fragmentary view similar to Fig. 3 but showing the bolt inbattery position and the sear in firing member disengaging position;

Fig. 6 is an end view of the bolt partially cross-sectioned to show thesear actuator engaged with the trigger bar in non-fire position;

Fig. 7 is an enlarged exploded view of the sear mechanism of thisinvention;

Fig. 8 is a fragmentary view partially cross-sectioned to show therelationship of the sear actuator lug with the trigger bar when innon-fire position during counter-recoil of the bolt; and

Fig. 9 is similar to Fig. 8 but showing the trigger bar in fireposition.

Shown in the figures is a firearm of the well-known Browning type havinga receiver 12, a bolt 13 slidably mounted therein for reciprocablemovement between a firing and a retracting position, a top plate bracket14 depending from the top side of such receiver, a trigger bar 15pivotally mounted on one side of such top plate bracket and a solenoid16 engaged to such trigger bar for actuation thereof. Solenoid 16 is soarranged that when charged the forward end of trigger bar 15, noted by17, is rotated downwardly clockwise from a non-fire to a fire positionand is returned by conventional spring means to non-fire position whenthe charging is stopped.

Provided in the side of trigger bar end 17 opposite top plate bracket 14is a step portion 18 which extends below the bottom side of such end andprovided in the inner side of the extending portion thereof is alongitudinal slot 19. A cam portion 20 leads from the bottom side oftrigger bar 15 to slot 19. Provided longitudinally along the side of topplate bracket 14 adjacent trigger bar 15 is a bar 21 which will befurther described hereinafter. The bottom side of slot 19 is arranged tobe aligned with the top side of bar 21 when trigger bar 15 is innon-fire position.

Provided in bolt 13 is a longitudinal bore 23 and a counterbore 22 inwhich there is slidably mounted a firing member 24 ireciprocable betweena firing position and a retracting position. Firing member 24 iscomprised of an extension 25 receivable by counterbore 22 and a striker26 receivable by bore 23. Provided in extension 25 is a longitudinalhole 27, which receives a compressible spring 28, and a rearwardlyadjoining vertical slot 29. The underside of the rear end of extension25 is slabbed, as noted by 30, and depending from the rear end thereofis a forwardly facing book 31.

Provided in the top side of bolt 13 is a recess 32 from the bottom sideof which a slot 33 and a hole 34, disposed forwardly thereof, extenddownwardly to counterbore 22. A pin. 5'7 is mounted in bolt 13 so as totraverse slot 33 and mounted thereon for rotational movement is acocking lever 35. The end of cooking lever 35 extending below pin 57,noted by 36, is provided with an actuating surface 43 which isengageable with the rear end of slot 29. The upper end of cocking lever32 is engageable with a V-slot 37 in top plate bracket 14 when bolt 13is adjacent battery position whereby such cocking lever is rotatedduring recoil of bolt 13 to move firing member 24 from firing toretracting position during the first part of the recoil of such bolt.Firing member 24 is maintained in retracting position during theremainder of the recoil of bolt 13 by engagement of a holding surface 64on the lower end of cocking lever 35 and the slidable engagement of thetop end of cocking lever 35 with the bottom side of top plate bracket 14as is best shown by Fig. 4. During counter-recoil of bolt 13 cockinglever 35 is counter-rotated by reengagernent with V- slot 37, moving end36 free of slot 29 to permit firing member 24 to be biased by spring 28to cocked position.

, Mounted in recess 32 is a member 38 comprised of a pin portion 39 andan arm portion 40.: Pin portion 39 is receivable by hole 34and extendsdownwardly therethrough to be slidably received by slot 29 and to engagethe rear end of spring 28 whereby firing member 24 is biased fromretracting to firing position. The front end of armpcrtion 4i)isterminated by :an upwardly arching arcuateportion 41, engageable bythe top portion of cocking lever 35, and the rear end is arranged to benormally contiguous one side of slot 33.

Mounted laterally through bolt 13 is a pin 42 which traverses firingmember 24 through slot 29 rearwardly of pin 39. Pin 42 traverses firingmember 24 by means of elongated slots 45 which permit uninterruptedreciprocal movement of firing member 24. A sear 46 is mounted on pin 42for pivotal movement between an upward holding position and a downwarddisengaging position. Sear 46 is comprised of an arm portion 4'7, whichextends rearwardly and downwardly through slot 29, land a body portion48 which extends vertically upward therefrom. Body portion 43 isreceived by an opening 58 in the rear end of bolt 13. In the front sideof body portion 48 is 'a recess shown by 49, arranged to receive therear end of firing member 24 and cocking lever 'end 36. A lateral indentSt) is provided in the bottom side of recess 49 to receive hook 31 whenfiring member 24 is in retracting position and sear 46 is in holdingposition. Formed by indent 563 is n rearwardly facing engaging surface51, which cooperates with book 31 for releasably holding firing member24 in the cocked position which is slightly forward of the retractingposition, and a land portion 44 arranged to be slidably engageable withbook 31 during reciprocation of firing member 24 between firing andcocked positions.

' In the upper side of recess 49 there is provided a locking surface 59which is engageable by actuating surface 43 of cooking lever 35. Lockingsurface 59 is so arranged that sear 46 is moved from disengaging toholding position by the engagement of actuating surface 43 therewithafter firing member 24 hasbeen moved thereby to retracting positionduring rotation of cocking lever 35.

Extending downwardly from the top side of bolt 13 is a hole 52 whichcommunicates with opening 58. Mounted for slidablc movement in hole 52is a cylindrical actuator 55. In the lower portion ofactuator 55 thereis provided a tongue portion 61 which is formed by a longitudinal groove64 and the bottom end of the actuator.

Groove 64 and tongue 61 are arranged to interlock with :a tongue 62 anda groove 63 provided in the upper portion of body portion 48 and therebysepiarably joins actuator 55 and sear 46. Projecting outwardly from thetop end of actuator 55 is a lug portion 56 which is adapted to beslidably receivable by slot 19 when sear 46 is in holding position andtrigger bar is in non-fire position. Lug 56 is movable along the bottomside of bar 21 during recoil of bolt 13 and is slidably engaged with thetopside of such bar during counter-recoil. Further, lug 56 is arrangedto be engageable with cam surface when trigger bar 15 is in fireposition whereby actuator 55 is deflectable downwardly to move sear 46to disengaging position.

To fire the firearm in which the sear mechanism of 7 this invention isembodied, solenoid 16 is charged whereby trigger bar 15 is pivoted fromnon-fire to fire position. It is to be noted that mechanical means mayalso be employed in actuating trigger bar 15. As has hereinbeforebeendescribed, when bolt 13 is in battery and 4 trigger bar 15 is innon-fire position, lug 56 on actuator 55 is received by slot 19 intrigger bar end 17. Therefore, when trigger bar 15 is depressed to fireposition, seat 46 is actuated thereby to disengaging position, releasingfiring member 24 which is biased forwardly by spring 28 to fire thechambered cartridge.

In the ensuing recoil of bolt 13, sear 46 is held in disengagingposition by the engagement of hook 31 with land portion 44 and by theengagement of lug 56 with the underside of bar 21 as it movestherealong. During the initial portion of the recoil movement, the topend of cocking lever 35 engages with V-slot 37 and thereby rotates suchcocking lever on pin 57. During the rotation of cooking lever 35,actuating surface 43 thereon engages the rear end of slot 29, actuatingfiring member 24 to retracting position, and finally engages withlocking surface 59 to move sear 46 upwardly to holding position wherebyhook 31 is received in indent 50, with the engagement of holding surface64 with the rear end of slot 29 holding the firing member in theretracting position. The upward movement of sear 46 to holding positionis arranged to take place after lug 56 has passed the'rear end of bar21. Sear 46 is maintained in holding position and firing member 24 inretracting position during the remainder of the recoil of bolt 13 by theengagement of the top of cocking lever 35 with the bottom side of topplate bracket 14.

In the following counter-recoil of bolt 13, lug 56 which was movedupwardly with sear 46 during the preceding recoil of the bolt movesalong contiguous the top side of bar 21 so that when cocking lever 35 iscounter-rotated by reengagement with V-slot 37, which moves actuatingsurface 43 thereon away from locking surface 59, sear 46 is secured inholding position by the slidable engagement of lug 56 with the top sideof bar 21. Also, during the counter-rotation of cocking lever 35, firingmember 24 is permitted to be biased slightly forward by spring 28,engaging surfaces 51 with hook 31 in the cocked position.

If it is desired to have automatic fire, trigger bar 15 is held in fireposition by solenoid 16. Therefore, when bolt 13 moves into battery, lug56 engages cam portion 20 of trigger bar 15 to move actuator 55 andconsequently sear 46 to disengaging position, again releasing firingmember 24 to fire the chambered cartridge.

If it is desired to cease fire, trigger bar 15 is permitted to return tonon-fire position. Consequently, when bolt 13 moves into battery, lug56, instead of engaging cam portion 20 to depress sear 46, is receivedby slot 19 in trigger bar 15 to engage sear 46 with trigger bar 15 andthereby the sear is held in holding position until the trigger bar ispivoted to fire position. Solenoid 16 is of a conventional adjustabletype whereby the fire position of trigger bar 15 may be adjusted so thatcam portion 20 actuates sear 46 whenbolt 13 is the proper distance awayfrom battery. Solenoid 16 is also arranged to normally bias trigger bar15 to non-fire position, consequently sear 46 is, by the engagementthrough actuator 55 with trigger bar 15, held resiliently in holdingposition during non-fire by the spring-bias of such solenoid;

Although a particular embodiment of my invention has been described indetail herein, it is evident. that many variations may be devised withinthe spirit and scope thereof and the following claims are intended toinclude such variations.

I claim:

1. In a firearm, a bolt reciprocable between a recoil and a batteryposition provided with a firing member spring-biased from a retracted to-a firing position, a scar pivotally mounted in said bolt for releasablylatching said firing member in said retracted position, means foractuating said sear comprising a cam, a lever for actuating said firingmemberto said retracted position ment of said bolt to said batteryposition, a trigger bar mounted on the firearm for pivotal movementbetween a fire and a non-fire position, means for actuating said triggerbar to said fire position and for resiliently biasing said trigger barto said non-fire position, interlocking means for releasably joiningsaid sear to said trigger bar when said bolt is adjacent said batteryposition and said trigger bar is in said non-fire position, whereby saidsear is movably responsive to actuation of said trigger bar.

2. In a firearm, a top plate bracket provided with a V-slot, a boltreciprocable between a battery and a recoil position, said bolt beingprovided with a slidable firing member normally biased from a retractedto a firing position, said firing member being provided with a verticalslot having an end wall, a sear provided. with a downwardly facinglocking surface, said sear being mounted in said bolt for pivotalmovement between a firing member holding position and a disengagedposition and being cooperable with said firing member for releasablylatching thereof in a cock position forward of said retracted position,a cocking lever pivotally mounted in said bolt to form an upper portionand a lower portion, said upper portion being cooperable with saidV-slot during reciprocation of said bolt for actuation of said cockinglever, an actuating surface on said lower portion, said actuatingsurface being engageable with said end wall for moving said firingmember to said retracted position and subsequently with said lockingsurface for pivoting said sear to said holding position during movementof said bolt to said recoil position and a holding surface on said lowerportion engageable with said end wall for holding said firing pin tosaid retracting position until said cocking lever is pivoted by saidbolt during movement thereof to said battery position.

3. In a firearm, a top plate bracket provided with a l-slot, a triggerbar pivotable between a fire and a nonfire position, actuating meanscooperable with said trigger bar for actuation of said trigger bar tosaid fire position and for normally biasing said trigger bar to saidnonfire position, a longitudinal slot in the front end of said triggerbar, a cam surface on the underside of said trigger bar, a boltreciprocable between a battery and a recoil position provided with aslidable firing member normally biased from a retracted to a firingposition, said firing member being provided with a vertical slot havingan end wall, a longitudinal bar fixedly mounted to said top platebracket parallel with the travel of said bolt, said longitudinal slotbeing alignable with the top side of said longitudinal bar when saidtrigger bar is in said firing position and with the bottom side of saidbar when in said nonfire position, a scar provided with a recess havingan upper locking surface for receiving the rear end of said firingmember, said sear being mounted in said bolt for pivotal movementbetween a firing member holding position and a disengaged position, anengaging surface in the bottom side of said recess cooperablewith a hookon the rear end of said firing member for releasably latching saidfiring member in a cocked position forward of said retracted position, acocking lever pivotally mounted to said bolt to form an upper portionand a lower portion, said upper portion being cooperable with saidV-slot for actuation of said firing member during reciprocation of saidbolt, an actuating surface on said lower portion cooperable with saidend wall for moving said firing member to said retracted position andsubsequently with said locking surface for pivoting said sear to saidholding position during movement of said bolt to said recoil positionand for release of said firing member into engagement with said sear insaid cocked position during movement of said bolt to said batteryposition, an actuator member interlocked with said sear for movementtogether, a lug protruding from said actuator member for slidingengagement with the bottom side of said longitudinal bar to hold saidsear in said disengaged position during movement of said bolt to recoilposition and said firing member to said retracted position and forsliding engagement with the top side of said bar after said sear isactuated by said cocking lever to said firing member holding positionwhereby said sear is maintained in said holding position until said boltis in said battery position, said lug being deliverable from the topside of said longitudinal bar into engagement with said cam surface whensaid trigger bar is in said fire position for automatically pivotingsaid sear to said disengaging position or into said longitudinal slotfor securing said sear in said holding position when said trigger bar isin said non-fire position.

4. In a firearm, a bolt movable in recoil responsive to actuation of thefirearm, said bolt being provided with a firing member spring-biasedfrom a retracted to a firing position, a pivotal sear for releasablylatching said firing member in said retracted position and a cockinglever pivoted during recoil movement of said bolt into engagement withsaid firing member for actuation thereof to said retracted position andinto subsequent engagement with said sear for pivotal actuation thereofinto position to releasably latch said firing member in said retractedposition.

5. In a firearm provided with a V-slot, a bolt reciprocable between arecoil and a battery position, said bolt being provided with a firingmember spring-biased from a retracted to a firing position, a searpivotable to a position for releasably holding said firing member insaid retracted position and a cooking lever pivotally mounted on atransverse pin to form an upper end engageable by the V-slot forpivoting said cocking lever during the reciprocation or" said bolt and alower portion reciprocable in a slot having an end wall provided in saidfiring memher, an actuating portion on said lower portion cooperablewith said end wall for actuating said firing memher to said retractedposition during pivotal movement imparted to said cocking lever duringmovement of said bolt to said recoil position, a recess in said sear forre ceiving said lower portion, a surface on the top side of said recessengageable by said actuating portion after said firing member is movedthereby to said retracted position for moving said sear into position tohold said firing member in said retracted position, an actuator memberinterlocked at the bottom end thereof to said sear for joint movementtogether, and a lug portion extending from said actuator to slidablyengage the top side of a bar mounted on the firearm longitudinal to themovement of said bolt for holding said sear in holding engagement withsaid firing member during movement of said bolt to said batteryposition.

6. In a firearm, a reciprocating bolt provided with a firing memberspring-biased from a retracting position to a firing position, a scarpivotally mounted in said bolt for releasably latching said firingmember in said retracting position, a pivotable cocking lever foractuating said firing member to said retracting position and forsubsequently pivoting said sear into engageable cooperation with saidfiring member responsive to recoil of said bolt, a longitudinal barmounted on the firearm parallel with the reciprocating travel of saidbolt, and means for connecting said sear with said bar duringcounter-recoil of said bolt whereby said sear is slidably maintained inholding engagement with said firing member.

References Cited in. the file of this patent UNITED STATES PATENTS1,846,156 Stange Feb. 23, 1932 1,966,592 Moore lluly 17, 1934 1,980,994Hofstetter Nov. 20, 1934 2,562,801 Maillard July 31, 1951

